Spinosaurus
Description S pinosaurus, meaning Spine Lizard, is a very large Theropod Dinosaur from Africa. It lived through the Albian and Cemonian stages about 103 - 93.5 Million years ago. Modern estimates range from 12-18m long and 7-20t tonnes in weight making it the largest known Theropod by some margin. However the lower lengths and high weight estimates hae been widley criticised for issues including the study's skull reconstructions and the other Theropods used for comparison. Two species have been named, S.aegyptiacus and S.morrocanus. Sail On its back were tall neural spines with estimates for their max height ranging from 1.5-2m. It has been suggested that these spines held up a skin sail and used it for Thermoregulation and display. However, the spines were not thin, but thick rods like seen in the fatty humps of modern day Bison. this has lead some to suggest that the spines held up a fatty hump. Regardless of their use, some sort of environmental pressure seemed to be forcing animals to grow some sort of sail. The un-related African iguanodont Ouranosaurus and its contempory Theropod Suchomimus both grew small sails. While at the same time the north american Carcharodontosaurid Acrocanthosaurus also had similar spines running down its back. Fossils Spinosaur fossils in general are very rare, and Spinosaurus is no exception. There are very few Spinosaurus remains that have been found, out of these the Holotype is the most complete. Specimens Six partial specimens of Spinosaurus have been described. The probable size of these individual spinosaurs can be estimated using comparison to known material from other spinosaurid dinosaurs. The estimates below are based on the Theropod Database and Dal Sasso et al., 2005. IPHG 1912 VIII 19, described by Stromer in 1915 from the Bahariya Formation, was the holotype. This specimen, from a subadult individual, was destroyed in World War II. However, detailed drawings and descriptions of the specimen remain. The individual is estimated to have been around 14 meters (46 ft) long and to have weighed about 6.7 tonnes (7.4 short tons). The material consisted of a maxilla (upper jaw) fragment, an incomplete dentary (lower jaw) measuring 75 centimetres (30 in) long, (the skull is estimated to have been 1.45 meters (5 ft) long with a mandible approximately 1.34 meters (4 ft) long), nineteen teeth, two incomplete cervical vertebrae, seven back vertebrae, dorsal ribs, gastralia, and eight caudal centra. The longest preserved vertebral spine was 1.69 metres (5.5 ft) long. IPHG 1912 VIII 19 is the specimen that Rauhut thought was chimeric. ParisCMN 50791, described by Russell in 1996 from the Kem Kem Beds of Morocco, is the holotype of Spinosaurus marocannus. The material it is based on includes a mid-cervical vertebra which is 19.5 centimetres (7.7 in) long, an anterior dorsal neural arch, an anterior dentary, and a mid-dentary. MNHN SAM 124, described by Taquet and Russell in 1998 from Algeria, consists of partial premaxillae, partial maxillae, vomers, and a dentary fragment. They came from an individual estimated to have been about 14 meters (46 ft) long and to have weighed about 6.7 tonnes (7.4 short tons). The skull is estimated at approximately 1.42 meters (5 ft) long. Office National des Mines nBM231, described by Buffetaut and Ouaja in 2002, consists of an anterior dentary from the Chenini Formation of Tunisia which is very similar to existing material of S. aegyptiacus. Specimen MSNM V4047 of S. aegyptiacus in al Museo di Storia Naturale di MilanoMSNM V4047, described by Cristiano Dal Sasso of the Civic Natural History Museum in Milan and his colleagues in 2005 from the Moroccan Kem Kem Beds, consists of premaxillae, partial maxillae, and partial nasals, which together measure 98.8 centimetres (38.9 in) long. The massive skull is estimated at 1.75 meters (6 ft) long, and the entire animal is estimated to have been around 16 to 18 metres (52 to 59 ft) in length and weighed around 7 to 9 tonnes (7.7 to 9.9 short tons). UCPC-2, also described by Dal Sasso et al. in 2005, consists of a 'fluted crest' from the region in front of the eyes. Other known specimens consist mainly of very fragmentary remains and scattered teeth. For example, teeth from the Echkar Formation of Niger have been referred to S. aegyptiacus. Possible material belonging to Spinosaurus has also been reported from the Turkana Grits of Kenya and the Cabao Formation of Libya (which dates to the Hauterivian stage), though the assignment of the later to the genus Spinosaurus is tentative. Category:Spinosaurids Category:Middle Cretaceous dinosaurs Category:Dinosaurs of Africa